: This is never going to happen but did you ever think about master chief
: already being infected by the flood. I'll explain. The flood tranmit
: themselves into hosts using spores, now if theses spores are small like
: pollen, wouldn't there have been a chance that MC is infected when he
: takes the infested Kees' nural inplant and inserts it into his head? If
: that wouldn't infect you then what will?

Aaaaahh. There is no evidence to suggest that the Flood spread by an airborne agent!!

From everything we see in the game. A person is infected from a spore
burrowing itself into the chest cavity of the victim.